Strut Tower Brace Bar?
10-12-2011, 03:52 PM
#81
One of the sponsors on this site did a test on a 4th gen with lowered susp and performance shocks and measured a 1/4 in deflection under cornering forces. I can't find it, I'll keep searching, but I read the post here...
Edit; It was BMR and the reply was quoted in a similar thread on 10-01-2010
Originally Posted by BMR Sales
Over the years this has definitely become a somewhat controversial mod. 12 years ago when we originally developed the strut tower brace for the 4th gen we measured almost 1/4" of strut tower movement on our test car equipped with higher rate springs and soft compound tires. If I remember correctly we were seeing over 1/8" movement even on the car in stock form when driven aggressively. If you are a drag racer, don't worry about it but if you like to push the car in the corners, it's probably the best $65 you'll spend....
Edit; It was BMR and the reply was quoted in a similar thread on 10-01-2010
Originally Posted by BMR Sales
Over the years this has definitely become a somewhat controversial mod. 12 years ago when we originally developed the strut tower brace for the 4th gen we measured almost 1/4" of strut tower movement on our test car equipped with higher rate springs and soft compound tires. If I remember correctly we were seeing over 1/8" movement even on the car in stock form when driven aggressively. If you are a drag racer, don't worry about it but if you like to push the car in the corners, it's probably the best $65 you'll spend....
Last edited by pewter2002; 10-12-2011 at 04:23 PM.
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Lsx_penguin (06-30-2021)
10-12-2011, 07:59 PM
#84
It's a HUGE difference in the way they act, react, mount and perform.
And that's the reason why a strut tower brace is almost mandatory and a shock tower brace is driveway jewelry.
Edit:
Sorry ...
And that's the reason why a strut tower brace is almost mandatory and a shock tower brace is driveway jewelry.
Edit:
Sorry ...
Last edited by mitchntx; 10-12-2011 at 08:08 PM.
10-12-2011, 08:14 PM
#85
^ Semantics. Read the full quote. According to BMR, enough stress is transmitted through the shock towers to cause a measurable amount of deflection DESPITE being a coilover design. Someone asked for proof of a STB being of any use at all b/c the loads are transmitted down through the K member/ chassis and NOT enough through the shock towers to warrant it. A major susp building manufacturer quoted the info from their own tests... Other than going out and repeating the test for myself somehow, I really don't know who to believe now. Respected road racers/chassis builders or a respected susp builder/supplier that specifically did a test and documented the results - hmmmmm...
10-12-2011, 09:50 PM
#86
10-12-2011, 10:58 PM
#87
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That's a good question.. maybe create some sort of sliding two piece STB that doesn't provide rigidity. Have something tied around it.. drive it around hard.. then measure how much the "tie thing" moved?
Does this make any sense?
Does this make any sense?
10-12-2011, 11:07 PM
#88
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It's funny, I was reading this thread and I was really buying the "shock tower braces are pointless" argument. My logic was:
- strut tower braces are good because they maintain geometry
- shock tower braces are pointless because suspension geometry isn't tied to the top of the strut in any way. Geometry depends only on the upper and lower a-arms, which I thought were connected to the k-member.
...and then I checked the drawing of the front suspension.
It turns out that the upper a-arm is actually connected to the top of the shock tower, not the k-member. Therefore, if the top of the shock tower moved, the suspension geometry would, in fact, change.
So I pose this question to the nay-sayers: why? What evidence do you have that negates this?
This is an honest question. I was on your side just 10 minutes ago. But now that I look, it seems that flex in our shock towers may have a very similar effect to flex in a strut tower.
- strut tower braces are good because they maintain geometry
- shock tower braces are pointless because suspension geometry isn't tied to the top of the strut in any way. Geometry depends only on the upper and lower a-arms, which I thought were connected to the k-member.
...and then I checked the drawing of the front suspension.
It turns out that the upper a-arm is actually connected to the top of the shock tower, not the k-member. Therefore, if the top of the shock tower moved, the suspension geometry would, in fact, change.
So I pose this question to the nay-sayers: why? What evidence do you have that negates this?
This is an honest question. I was on your side just 10 minutes ago. But now that I look, it seems that flex in our shock towers may have a very similar effect to flex in a strut tower.
10-12-2011, 11:12 PM
#89
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Read my post below that I posted early. I'm not a big STB fan, but I'm not against them. But, I was thinking. A few people, including suspension vendors, have mentioned they had to jack the front of the car up in order to fit a STB brace on the car. That is showing their is SOME flex in the front end. So say it was installed just as a "strengthening" brace, and not a proven suspension benefit, just the same way people spend $150 to put a TA girdle on their 10 bolt, because they say it strengthens it, when nobody has real proof a TA girdle strengthens a weak 10 bolt. They just see 2 extra supports and think it must help, which is the same concept as a STB.
Playing devil's advocate here..
Playing devil's advocate here..
My old 97 Trans Am came with a STB, and I rocked it for about a year and a half. I ended up taking it off and giving it to my friend and actually liked the ride BETTER WITHOUT IT. My personal experience, but I'm sure some of you here will tell me my personal experience is scientifically wrong. 
10-13-2011, 06:37 AM
#91
Launching!
Unbalanced Engineering reported that there was "almost no load" going through the STB.
The 4th gen front end puts most of that 1.4+g (on Hoosiers) lateral loading seen in a corner through the K member.
The upper arm mount has bolt holes significantly larger than the through bolts yet we never see any movement up there so long as things are torqued properly.
However, just about every single one of us who has ever mounted up a set of large sticky tires on the front has had their alignment slip on the lower arm. This despite the lower arm having MUCH more clamping (larger bolts / washers at a greater torque value). This despite most of us going beyond the required factory torque setting.
Last edited by Ironhead; 10-13-2011 at 06:52 AM.
10-13-2011, 10:55 AM
#94
Launching!
Urban legend.
*shrug* Look.... if you (or anyone else) think you need one, buy one and be happy.
Just don't expect the rest of us, (whose self esteem is NOT dependent upon the interweb hordes agreeing with our decisions and patting us on the back for being clever), to agree with you when questions are asked.
10-13-2011, 11:05 AM
#95
Thats the reason I didnt get the 3point... I already replaced my glass once.. **** that. Ill be making a cross bar that will intentionally move and show how much afterwards. This should be sufficient proof as to their validity as a "suspenstion" versus "appearance" mod...
10-13-2011, 01:36 PM
#96
TECH Senior Member
1/8" to 1/4" is a large amount of variance...
if the shock towers had that much relative movement, there are several points to consider:
- camber would become misaligned;
- that much movement would cause metal fatigue at the "hinge" point which would eventually fracture;
- the body panels would become misaligned.
Also think about this: the top of the shock towers support the weight of the front of the vehicle (1900lb...?)...
if the shock towers deflected so much/easily then there would be a serious problem and it would be pointless to get camber/caster aligned.
if the shock towers had that much relative movement, there are several points to consider:
- camber would become misaligned;
- that much movement would cause metal fatigue at the "hinge" point which would eventually fracture;
- the body panels would become misaligned.
Also think about this: the top of the shock towers support the weight of the front of the vehicle (1900lb...?)...
if the shock towers deflected so much/easily then there would be a serious problem and it would be pointless to get camber/caster aligned.
10-13-2011, 01:59 PM
#97
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I was just doing a google trying to figure out why strut suspensions deflect so much more than our shock/a arm setups. Couldn't find too much. Would be nice to see some sort of diagram showing where force is applied comparing both types of suspensions.
10-14-2011, 06:57 AM
#100
Launching!
I really don't care if you have the brace or not. I really don't care if ANYBODY has the brace on their car. If you feel you need it, great. If you like it, great.
I've had one on my car in the past. I don't have one now. I explained why. I'm comfortable with that and don't need others to support my viewpoint.
That's as far as it goes for me.